Brett Felton had plenty of training in the U.S. Army’s 10th Mountain Division, the unit he served with in Iraq from 2006-2007.

But it was his commitment to fellow Christians halfway around the world that prompted him to go back.

"People say, 'You're crazy for doin' this,'" Felton told "60 Minutes" producer Jeff Newton, who met him in February, while working on a segment that aired Sunday. "I think people are crazy for not doing their part, to be honest with you."

"To me, for the Christians here, it would be an honor to give my life helping these people."

Felton, a 28-year-old from Troy, Michigan, returned to the cradle of Catholic faith during his Army service in Iraq, according to the National Catholic Register's Joan Frawley Desmond.

Recently, while studying in Lebanon, he slipped into Iraq, where Christians have been fleeing the advance of the Islamic State group (ISIS). The "60 Minutes" crew caught up with him in Bakufa, an abandoned Christian village north of Mosul.

While he was in Iraq last time with the Tenth's 2nd Battalion, 14th Infantry Regiment, he was there this time, he said, as a "soldier of Christ."

Newton, who described the man as "tattooed out like a biker," with images of Christ on his body, found Felton to be a "hardcore Christian."

Newton and correspondent Lara Logan encountered "a few Christian men" who had formed militias to save their villages, north of Mosul. They lacked training, good weapons, and funds.

"When you're with them, you have this terrible feeling that many of them would be massacred if the Islamic State really turned its attention to taking back those those villages," Logan said.

Felton was training them in urban warfare: how to enter and clear a room, how to check for suicide vests, and how to drag your wounded to safety.

Brett Felton had plenty of training in the U.S. Army’s 10th Mountain Division, the unit he served with in Iraq from 2006-2007. But it was his commitment to fellow Christians halfway around the world that prompted him to go back.